Divide Polygon in equal areas

[KonradHentze1]

Dear community,

we are working with a lot of big forest parcels and want to divide them into (exact) 1ha, 0,25ha parcels and so forth. Is there any kind of algorithm which could do this automatically? Up to now, we are overlaying polygon-rasters of smaller size then the desired output and merge the small squares. But of course the parcels we get cant fit 100% in our forest area (squares in irregular polygons). Other solutions are drawing parcels by hand and estimating the area, calculating it as an attribute, take a small bit of or ad a bit and so forth until we get the area of 1 Hectar.

Do you guys have any idea how we can automate this process? and if not as "divide polygon in 0,25 ha pieces" something like " divide polygon in 20 equal areas"? It would save us time and space in our layers :rolleyes:

I fear this is to heavy to calculate but still hope for suggestions

thanks for you input, regards Konrad

[JulianaWilhoit]

But since ArcMap cannot import scripts, its useless.

Just for clarification, ArcMap does support the use of scripts in languages such as Python and in 10.0 (but not 10.1) VBA.


Have a great day!

Juliana

[DanLee]

Hi Konrad,

I don't have an answer to your question, but I need clarifications for future tool design/enhancement.

You seem to think that the "dividing parcel by area" in Parcel Fabric is 100% what you need. I am not an expert in Parcel Fabric, but from reading the help topic and seeing the illustrations, I got the impression that the "dividing parcel by area" divides a parcel into multiple new parcels based on a specified starting direction; so you would end up having one row of new parcels horizontally (west�??east) or vertically (north�??south). Do you need multiple rows and columns of subdivisions as the image you provided shows, which would be a lot more difficult to do?

There are unlimited ways of dividing a polygon into equal-area polygons without the horizontal or vertical constraint. Creat Fishnet tool seems to give you something close; a rotated fishnet may fit more cells depending on the shape of the polygons. But still there could be many ways to divide the remaining border areas where full cells of fishnet cannot fit. Can you illustrate with a drawing how you would resolve those areas? Do you want the dividing lines to follow the same orientation as the fishnet lines, horizontal/vertical or rotated?

The similar questions go to Paul: there are many ways to divide an irregular polgyon into two. Can you give more specifications? Does Parcel Fabric (if you have the right license) give you the right solution? If not, why not?

Thanks for your input in advance.

[KonradHentze1]

Hey, Dan

thanks for your input. Indeed it ist kind of difficult. The ideal output would contain multiple rows and columns. I did not now that the parcel editor would create polygons starting from one direction only. But still it would work for us: We could first divide the are from East to West and then further from North to South. So we would create subareas as long as we would receive our desired output area.

To be honest, at the moment I don't have any solution how to treat the area around the fishnet containing only subsets of squares. One would be to calculate their area and manually merge those ones who make up approximately the same area as one fishnet Square.

regards

[DanLee]

Hi Konrad,

Thanks for the feedback. That is a good use of the parcel editor tool; I can imagine that it still requires some manual calculation in order to specify how to divide a parcel. I will keep your case in mind for future automation and tool design.

[LindseyMessinger]

I am also attempting to divide irregular shaped polygons into polygons of equal area.  I am doing a research project where I want to sample random areas within a field.  I need to generate random points within these fields, one in every 4 acre piece of the field.  I could use the fishnet tool to make a grid, however, since the fields are irregularly shaped, this gets complicated at the edges.  I know others have suggested using the parcel fabric editor but this seems very complicated and I don't have topology estalished with my fields and am not even sure how to create a parcel fablic from a polygon feature class.  Any advice would be apperciated!

Lindsey

[DanLee]

Would you consider keeping relatively larger fishnet polygons (say: > 50% of a full fishnet cell) and eliminating relatively small ones by merging them with neighboring polygons, along the edge? If so, you can try this:

1. Use Select Layer By Attribute tool to select the fishnet polygons if they are < cellsize.
2. Use Eliminate tool (Data Management toolbox - Generalization toolset; ArcInfo license) to merge the selected polygons with neighbors.

[iI]

Good Morning,

We had the same problem and we used the automatic command in Autocad (with APLUS plug-in) called ARED.
To check tutorial about this exact comand called AREA DIVIDE = ARED: https://www.facebook.com/media/set/?set=vb.294901707192311&type=2

Hope it is useful for your problem.

[LisaKing1]

so I have been reading and reading, and I only see in the parcel fabric thing where you can divide 1 selected polygon in the fabric, is that true, I have like 100 I"d like to divide, fishnet doesnt' work because while the polygons are extremely similar, they are sections actually in Ohio, but they are not perfect, so the fishnet ends up not aligning. I just want to divide a bunch of then at once. Am I crazy or is that not possible with fabric tool.

[AaronKing]

so I have been reading and reading, and I only see in the parcel fabric thing where you can divide 1 selected polygon in the fabric, is that true, I have like 100 I"d like to divide, fishnet doesnt' work because while the polygons are extremely similar, they are sections actually in Ohio, but they are not perfect, so the fishnet ends up not aligning. I just want to divide a bunch of then at once. Am I crazy or is that not possible with fabric tool.

you are not crazy, and parcel editor wont do a bunch at once, as i understand it.

also, WASSUP CUZ!

[ElliotHartley]

Just stumbled on this thread looking for something else... thought I might contribute though.... I can relate to having an ArcMap 'basic'/arcview licence and needing one feature in other licence levels!

You might want to check out the repeating shapes tool here to see if it helps:

http://www.jennessent.com/arcgis/arcgis_extensions.htm

Not ideal but then if we want ideal we have to pay for it 😉